JPS6359556B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently manufacturing a printed wiring board with excellent bonding strength between an insulating substrate and metal foil, solder heat resistance, and mechanical strength. So-called printed wiring boards, which are constructed by laminating conductors made of metal foil such as copper foil on an insulating substrate with adhesive, are used in fields such as various home appliances, computers, communications devices, and various instruments. Used in large quantities. Conventionally, as insulating substrates for printed wiring boards,
Composite sheets are used that combine thermosetting resins such as epoxy resins, phenolic resins, and unsaturated polyester resins with base materials such as paper and synthetic glass fibers. Since these all use thermosetting resins, not only is it complicated to recover and dispose of the solvent during substrate manufacturing, but the solvent also scatters into the atmosphere, significantly deteriorating the working environment, and also causes the resin to harden. There were problems such as it took a lot of time and was not economical. The inventors of the present invention investigated the purpose of improving the above-mentioned drawbacks of the manufacturing process and easily and inexpensively manufacturing printed wiring boards with even better thermal and mechanical properties, and found that polyphenylene sulfide resin By using a plate-shaped molded product made of a composite composition of glass fibers and glass fibers as an insulating substrate, process problems caused by the use of solvents and curing of resin can be solved, and in addition, it is possible to solve the problem of using conventional thermosetting resins. It was proposed that a printed wiring board with characteristics equal to or better than printed wiring boards could be obtained. However, the polyphenylene sulfide resin (hereinafter abbreviated as PPS) used in this method has high chemical stability and crystallinity, so polyvinyl acetal, phenolic-nitrile rubber, and epoxy Even if a vinyl acetate-based adhesive or a vinyl acetate-based adhesive is used, the bonding strength between the insulating substrate and the metal foil and the soldering heat resistance cannot be sufficiently satisfied. For example, JP-A-54-
Publication No. 85380 uses an epoxy adhesive to bond a PPS substrate and metal foil, but it is not an efficient process because it takes a long time for the adhesive to harden. Since the heat resistance of the adhesive is low and the bonding temperature cannot be increased, there is a problem that sufficient bonding strength and soldering heat resistance cannot be obtained. Therefore, the present inventors aimed to further improve the bonding strength and solder heat resistance between the insulating base material and the metal foil in a printed wiring board whose insulating substrate is a composite material of PPS and glass fiber, and to further increase its productivity. After studying the objectives, we found that the above objectives can be effectively achieved by using an epoxy silane adhesive as the adhesive and by employing a bonding temperature higher than the melting point of PPS. That is, the present invention involves applying an epoxy silane adhesive to the joint when laminating a metal foil and a composite substrate made of 85 to 20% by weight of PPS and 15 to 80% by weight of glass fibers with a length of 0.1 mm or more by face-to-face bonding. The present invention provides a method for producing a printed wiring board, which comprises heating and pressurizing the polyphenylene sulfide resin at a temperature higher than the melting point of the polyphenylene sulfide resin. The PPS used in the present invention has the structural formula

A polymer containing 90 mol% or more, preferably 95 mol% or more of repeating units represented by the formula, and has a melt viscosity of 50 to 50,000 when measured at a temperature of 300°C and an apparent shear rate of 200/sec. Poise, preferably in the range of 100 to 5000 poise, is suitable. Note that ordinary additives such as antioxidants, heat stabilizers, lubricants, crystal nucleating agents, ultraviolet absorbers, colorants, fillers, and mold release agents can be added to the PPS used. It is also possible to blend small proportions of other types of polymers within a range that does not impede the purpose. The form of the glass fiber used in the present invention is chopped fiber, chopped fiber mat, continuous filament mat, woven fabric, knitted fabric, or two or more types thereof, as long as the length in the composite substrate is 0.1 mm or more. It may be used in any combination, but
Mat-like or fabric-like materials such as knitted fabrics are easy to handle and have excellent mechanical strength of the composite substrate, and are particularly suitable for use. The content of glass fiber is 15 to 80% by weight, especially 20%.
A content of 75% by weight or less is suitable; if it is less than 15% by weight, sufficient mechanical strength cannot be obtained, and if it is more than 80% by weight, the mechanical strength is even lowered, which is not preferable. In addition, the length of the glass fiber contained in the composite substrate is
A thickness of 0.1 mm or less is also not preferable because its mechanical strength will be insufficient. There are no particular restrictions on the method for manufacturing a composite substrate as an insulating base material by combining PPS and glass fibers, but for example, (1) melting and kneading PPS and glass chopped fibers using an extruder or the like, and then extruding A method for producing a plate-shaped molded product by molding or injection molding, and (2) glass fiber in the form of chopped fiber pine, continuous filament pine, woven fabric, etc., and in the form of powder, pellet, sheet, etc. Examples include a method of producing a plate-shaped molded product by alternately piling up PPS and heating it above the melting point of PPS, pressurizing it, and cooling it. Compared to conventional methods using thermosetting resins, these methods not only eliminate the need for extra steps such as recovering a solvent, but also eliminate the need to harden the resin, making them extremely efficient. There is no particular limit to the thickness of the composite board, and it is usually
A range of 0.1 to 5.0 mm is selected. The most suitable metal foil to be surface-bonded to at least one surface of this composite substrate is copper foil, but other foils such as nickel, aluminum, gold, silver, tin, and zinc can also be used. The epoxy silane adhesive used in the present invention is
general formula

[expression] and

It is represented by the formula: R represents an alkyl group having 1 to 6 carbon atoms, and R' represents an alkyl group having 1 to 3 carbon atoms. Examples of these epoxysilane adhesives include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. -Epoxycyclohexyl)propyltrimethoxysilane, etc. Even if commonly used silane-based, polyvinyl acetal-based, phenolic rubber-based, or epoxy-based adhesives are used instead of this epoxy silane adhesive, the bonding strength between the composite substrate and metal foil is insufficient. Therefore, the soldering heat resistance is also not fully satisfactory. Specific examples of manufacturing printed wiring boards by the method of the present invention include the following two methods. (A) Apply an epoxy silane adhesive on the composite substrate and/or metal foil obtained by method (1) or (2) above.
A method of applying the product to a thickness of 0.5 to 30 μm and heat-pressing it under a pressure of 10 to 150 kg/cm ² at a temperature above the melting point of PPS, for example, about 280 to 350°C. (B) When laminating PPS and glass fiber using method (2) above, use an epoxy silane adhesive of approximately 0.5 to
Directly overlap metal foil coated with a thickness of 30μ,
Examples include a method of directly obtaining a printed wiring board by heating above the melting point of PPS, pressurizing it, and cooling it. In these methods (A) and (B), if the heating temperature is below the melting point of PPS, it is not preferable because a long time is required for bonding and the resulting bonding strength is insufficient. Also,
In the methods (A) and (B) above, if a metal foil is punched out in advance into a pattern, and an epoxy silane adhesive is applied to it and bonded to a composite board, the desired printed wiring board can be directly obtained. Further, the desired printed wiring board can also be obtained by pattern etching the metal foil by a subtractive method after bonding. The time required for heating and pressurizing in methods (A) and (B) above is 1 minute, especially 5 to 30 seconds in case of method (A), and 5 minutes or less, especially 1 to 3 minutes in case of method (B). is sufficient, and efficient bonding can be achieved in an extremely short time. In particular, method (B) allows printed wiring boards to be manufactured from raw materials in one step, which is extremely advantageous in terms of process. Thus, the printed wiring board obtained by the method of the present invention has extremely excellent bond strength and solder heat resistance between the board and metal foil, and also has good thermal and mechanical properties, so it is highly expected to be applied to the electrical industry field. be done. The effects of the present invention will be further explained below with reference to Examples. Example 1 PPS (“Ryton” P-4 manufactured by Philips)
The powder was evenly sprinkled on glass continuous fiber pine (manufactured by Asahi Fiberglass Co., Ltd., M9600, basis weight 600 g/m ² ), and then SH6040 (manufactured by Toray Silicone Co., Ltd., γ- Glycidoxypropyltrimethoxysilane) was applied diluted or undiluted to a thickness of about 10 microns, stacked and fed between flat molds in a hot press set at 330°C to produce 5kg. After applying a pressure of / ^cm2 and heating for 3 minutes, the mold was transferred to a cooling press set at 150℃ and cooled for 2 to 3 minutes under a pressure of 30Kg/ ^cm2 to form a glass with a thickness of 1.6mm. A printed wiring board with a fiber content of 35% by weight was created. The peel strength and solder heat resistance between the copper foil and the board of this printed wiring wave were measured according to JIS C6481, and the peel strength was 1.8 Kg/cm ² The solder heat resistance was excellent at >270°C/20 seconds. was. Furthermore,
Printed wiring boards could be manufactured very efficiently and in a short time. Example 2 PPS (“Ryton” P-4) was subjected to extrusion molding,
A sheet with a thickness of 0.7 mm was formed. Next, the above PPS and continuous glass fiber mat were alternately laminated, heated, pressed and cooled in the same manner as in Example 1 to obtain a composite substrate with a thickness of 1.6 mm and a glass fiber content of 40% by weight. On the other hand, various adhesives shown in Table 1 were applied to a copper foil with or without dilution to a thickness of about 10 microns. Next, the above PPS composite substrate and the adhesive coated side of these copper foils were laminated and pressed in a press heated to 330°C.
Heat and pressurize for 30 seconds under a pressure of 20Kg/cm ² to melt the copper foil bonding surface of the PPS composite board, then feed it into a cooling press set at 150℃ and heat it under a pressure of 30Kg/cm ^2.
After cooling for 30 to 60 seconds, a printed wiring board was created. The peel strength and solder heat resistance of each printed wiring board were evaluated in the same manner as in Example 1.
Shown in the table.

【table】

[Table] As is clear from Table 1, printed wiring boards (No. 1,
2) uses another silane adhesive (No.
3, 4) and those using other adhesives (No.
5 and 6), the peel strength and soldering heat resistance were significantly superior. Example 3 PPS (“Ryton” P-4) powder and 10 mm long glass chopped fibers (Asahi Fiber Glass, CS10MA404) were mixed so that the glass fiber content was 40% by weight. It was fed into a shell mixer and mixed for 20 minutes to obtain a flocculent appearance mixture consisting of PPS powder and glass chopped fibers. This mixture was fed between a hot press and Example 1
By pressing and cooling under the same conditions as above, a composite substrate with a thickness of 1.6 mm was obtained. On the other hand, as an epoxy silane adhesive on copper foil,
SH6040 was applied with or without dilution to a thickness of approximately 1 micron. Next, the above PPS composite substrate and the adhesive-coated side of this copper foil were laminated, and heated at temperatures of 150, 200, 250, 300, and 330°C for 30 minutes under a pressure of 200 kg/cm ² . After being heated and crimped for seconds, it is fed into a cooling press set at 150℃, and heated at a pressure of 30Kg/ ^cm2 for 20 to 30 minutes.
After cooling for 60 seconds, a printed wiring board was created. These were evaluated in the same manner as in Example 1, and the results are shown in Table 2.

[Table] As is clear from the results in Table 2, below the melting point of PPS (Nos. 7 to 9), there is no adhesion between the copper foil and the PPS composite board, but above the melting point of PPS, no adhesion is observed. The adhesives (Nos. 10 and 11) had excellent peel strength and soldering heat resistance.

Claims (1)

[Claims] 1 Polyphenylene sulfide resin 85-20% by weight
When laminating a composite substrate made of 15 to 80% by weight of glass fiber with a length of 0.1 mm or more and a metal foil by surface bonding, an epoxy silane adhesive is present in the joint, and a polyphenylene sulfide resin is applied. A method for manufacturing a printed wiring board, characterized by heating and pressurizing at a temperature above the melting point.